Environment-conscious industries are continuously laboring toward the goal of removing pollutants from contaminated water to make the water safe at both the ground level and the consumer level. Government-regulated agencies establish limits for many common industrial pollutants. These limits tend to become stricter as pollution reduction and removal technology proves effective at accomplishing previously-established requirements. Consequently, both ground and consumer level water continue to improve in terms of both purity and safety.
Among the methods employed to reduce or remove pollutants, bioremediation constitutes an effective and desirable technology. In a broad sense, bioremediation includes the use of microorganisms that digest pollutants as a source of food, including nitrogen and carbon compounds. Bacterial metabolism converts the pollutants to metabolites having a simple chemical structure, sometimes degrading the pollutants completely to carbon dioxide and water in an aerobic process, or to methane in an anaerobic process. In any respect, the metabolites produced by the bacteria typically have no adverse environmental effects.
Selenium is sometimes a major contaminant in waste water, including mine drainage and agricultural irrigation water. The present selenium maximum level for drinking water mandated by the Environmental Protection Agency is 0.05 parts per million (ppm). Several chemical processes have been developed for selenium removal from waste water, but they tend to be relatively expensive and require an undesirably large amount of time and machinery. Mining companies and government agencies such as the Bureau of Reclamation are incurring large costs to remediate selenium from mine drainage and irrigation water.
Accordingly, it is desirable to provide a method and system for removing selenium from waste water in a cost and time efficient manner. It is also desirable to provide such methods and systems that can replace some conventional chemical processes for selenium removal with biological processes and thereby reduce the requisite time, machinery, and operational costs for performing the processes. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.